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The death of diesel, thanks to Volkswagen

As European scientists note, ‘emissions of diesel cars have been underestimated up to 20-fold in officially announced data.’

Green wheels columnist Peter Gorrie says It would have been better for regulators to conduct more stringent emissions years ago, as that may have revealed "Volkswagen’s deception much sooner." (INGO WAGNER / AFP/GETTY IMAGES)

What fallout has drifted down from the Volkswagen scandal during the past two weeks?

I can’t say, because this column had to be written just after the world’s Number One car-seller admitted to cheating on emissions tests.

But it is possible to conclude that while the elaborate deception is galling, particularly for those who care about toxic air pollution, it could provide benefits.

Most important, it raises questions about the validity of all the fuel-economy tests that are central to government efforts, here and around the world, to cut greenhouse-gas emissions and toxic pollution from vehicles.

Since the start of Green Wheels, I’ve noted the large gap between official test results and real-world fuel consumption. Some carmakers have gamed the results, employing everything from over-inflated tires to Volkswagen’s sophisticated software. But even without those tricks, and despite improvements over the years, the laboratory test cycles don’t match on-road driving patterns or styles.

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Some argue the discrepancies don’t really matter because, at least, fuel consumption and emissions are dropping, even if not to the actual numbers claimed. But the differences between test and real-world results vary widely among different vehicles. With some, the gap is small; in others, gaping. So it’s impossible to know whether there’s really a consistent downward trend.

On the day this column was written, the U.S. Environmental Protection Agency told carmakers to expect tighter controls.

Its brief letter states: “EPA may test or require testing on any vehicle at a designated location, using driving cycles and conditions that may reasonably be expected to be encountered in normal operation and use, for the purposes of investigating a potential defeat device.”

To decode: Carmakers provide emissions and fuel-economy data to the EPA, which spot checks their results by running randomly selected cars on a dynamometer. A regulation imposed back in 1999 allows these spot checks to include on-road drives, where Volkswagen-style devices would not kick in. These tests will, finally, be part of the procedure.

On-road tests should detect any significant deviations from dynamometer results. However, they won’t generate official fuel-economy scores because they can’t ensure all vehicles are tested under identical conditions — the very reason the tests are conducted in a laboratory.

It would have been better for the EPA to conduct these additional tests over the past 16 years. It might have caught Volkswagen’s deception much sooner.

But this step is just one of many required to improve the fuel-economy tests, for both diesel and gasoline, which still over-state progress toward fuel economy and undermine the standards. They shouldn’t be entrusted to carmakers. They should attempt an on-road component, and be done with vehicles fitted exactly as for customers.

Diesel should disappear. Here’s one of many reasons why: In 2013, scientists in Germany and Luxemburg reported that, in Europe: “expected greenhouse-gas savings initiated by the shift to diesel cars have been overestimated,” and “toxic … emissions of diesel cars have been underestimated up to 20-fold in officially announced data.”

Tougher standards likely won’t alter that situation. After all, European carmakers have just asked regulators for much more lenient standards for real-world tests.

The push for diesels has held back imperfect but better alternative technologies.

Cars pose environmental problems that won’t be solved just by dumping diesel. But it would help.

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